From 4608d199a40eeb4a236fa1f74efd97200e50567c Mon Sep 17 00:00:00 2001 From: Lucian Petrut Date: Wed, 17 Oct 2018 11:46:46 +0300 Subject: [PATCH] Document distributed lock configuration We're now relying on distributed locks in order to prevent race conditions that affect instance failover handling. This change documents the required configuration updates and prerequisites. Change-Id: Ic08b28ac16faea673838aa2dc05c1dd70806280e --- doc/source/configuration/index.rst | 28 ++++++++++++++++++++++++++++ doc/source/install/prerequisites.rst | 9 +++++++++ 2 files changed, 37 insertions(+) diff --git a/doc/source/configuration/index.rst b/doc/source/configuration/index.rst index db72b559..6e4e644e 100644 --- a/doc/source/configuration/index.rst +++ b/doc/source/configuration/index.rst @@ -187,6 +187,34 @@ configured. For this, check the `nova PCI passthrough configuration guide`__. __ https://docs.openstack.org/nova/queens/admin/pci-passthrough.html +Distributed locking configuration +--------------------------------- + +In order to avoid race conditions, our driver relies on distributed locks. A +distributed lock backend such as etcd, mysql or a file share will have to be +configured. + +The following configuration will use etcd 3 as a lock backend: + +.. code-block:: ini + + [coordination] + backend_url = etcd3+http://etcd_address:2379 + +.. note:: + + The ``etcd3gw`` python package is required when using etcd 3. This does not + apply to the v2 etcd API, which may be requested through + ``etcd://etcd_address:2379``. + +In order to use a file share, set the following: + +.. code-block:: ini + + [coordination] + backend_url = file:////share_addr/share_name + + Configuration options --------------------- diff --git a/doc/source/install/prerequisites.rst b/doc/source/install/prerequisites.rst index 257f3277..a0d914fa 100644 --- a/doc/source/install/prerequisites.rst +++ b/doc/source/install/prerequisites.rst @@ -233,6 +233,15 @@ Cluster Driver to be usable, the Hyper-V Cluster nodes will have to be joined to an Active Directory and a Microsoft Failover Cluster. The nodes in a Hyper-V Cluster must be identical. +In order to avoid race conditions, our driver relies on distributed locks. A +distributed lock backend such as etcd, mysql or a file share will have to be +configured. + +For more details about available distributed lock backends, check the +`list of drivers supported by tooz`__. + +__ https://docs.openstack.org/tooz/latest/user/drivers.html + Guarded Host configuration (Shielded VMs) -----------------------------------------